This invention relates to a pinching tube cutting device to crosswise cut a tube made of plastic material.
One already knows of such tube cutting pliers. Such pliers are made up of two handles connected to each other around a transversal axis, of which one handle contains a cutting blade at its end, while the end of the other contains a seat designed to receive the tube to be cut.
In general, a tube cutting device contains a blade with a rectangular sharp edge. This presents the inconvenience of necessitating a considerable strain at the beginning of the cut. In effect, the blade attacks the tube tangentially and the tube has the tendency to slightly flatten in such a way that the contact zone between the blade and the tube is a line, which makes the beginning of the cut difficult, with the risk of crushing the tube and, also, deforming the tube.
This inconvenience manifests itself more particularly where the tubes are of a large diameter and, more specifically, where the proportion between diameter/thickness of the tube is large and the tube is then of a lesser rigidity.
In order to partially compensate for this inconvenience, it has been proposed tube cutting objects which allow the creation of a cut called pulled or xe2x80x9cwhile pullingxe2x80x9d; that is to say that instead of placing the pivoting axis near the coincidental line with the blade, the axis is moved away, such that the classic cut is associated with a translation of movement from the blade to the object to be cut.
Others have proposed tube-cutting pliers containing, like tube cutters of the guillotine type, a blade with two sharp edges making an obtuse salient angle and including a point which allows the beginning of the cut with little effort while avoiding the crushing of the tube, however, at the end of the cut the two sharp edges simultaneously and tangentially attack the internal surface of the tube, which necessitates a considerable effort.
It would be possible, however, to remedy this inconvenience by using a blade such that the two sharp edges form an acute angle, but this would necessitate a considerable path for the blade, and a significant spread of the handles of the tool which would not facilitate its use.
One also knows, from document CA-A1 178 426, a tube cutting device which contains a blade with two sharp edges forming between them an angle of between 70xc2x0 and 100xc2x0, and preferably 85xc2x0, with the sharp edge closer to the pivoting axis making an angle with the horizontal between 20xc2x0 and 60xc2x0, and preferably 55xc2x0, while the other sharp edge makes an angle with the horizontal between 20xc2x0 and 60xc2x0, and preferably 40xc2x0.
If this device allows the production of a more efficient cut than other existing devices, it does not solve the other inconveniences, such as the angle that the sharp edges form which necessitates a large opening of the handles and requires a considerable force at the beginning of the cut and limits the capacity of the cut and, at the end of the cut, despite the angular gap of the sharp edges compared to the horizontal, there exists a phase where the sharp edges attack the internal side of the tube from the interior in a simultaneous and tangential manner, which as a consequence necessitates a considerable effort.
The present invention has as an aim to remedy these diverse inconveniences by proposing a pinching tube cutting device of which the use is easier than that of the existing devices, since it does not necessitate a considerable effort at the beginning or at the end of the cut.
The pinching tube cutting device of the present invention consists of two handles connected to each other in such a way that the two handles pivot around a transversal axis, of which one is fitted at its end with the cutting blade, and the end of the other handle consists of a hollow seat designed to receive the tube to be cut. The device is characterized by the two sharp edges of the blade forming an obtuse, salient angle between them between 120xc2x0 and 150xc2x0, and in such a manner that the angle formed by the sharp edge furthest from the transversal axis and a line passing through the point of the blade is larger than that formed by the other sharp edge and the line. The point describes, during its pivoting, a circular arc which cuts the segment of the line which joins the pivoting axis and the center of the tube of the largest diameter possible to rest in the seat, in such a way that the beginning of the cut is achieved by the point and the end of the cut is achieved only by the sharp edge the furthest from the pivoting axis.
According to an additional characteristic of the device of the invention, the sharp edges of the blade make an angle of 135xc2x0.
According to an additional characteristic of the device of the invention, the circular arc which is described by the point of the blade cuts the right segment joining the pivoting axis in the center tube of the largest diameter possible to rest in the seat at a point situated in the middle region of the radius of the tube.
According to an additional characteristic of the device of the invention, the angle formed by the sharp edge furthest from the pivoting axis and the line passing by the point of the blade and the axis is double that formed by the other sharp edge and the line.
The tube cutting device according to the invention is designed to cut in an optimum manner a tube of a diameter which corresponds to that of the seat. It allows, however, the cutting of tubes of a smaller diameter, even those where the diameter is too small to allow the beginning of the cut by means of the point of the blade. In this case, the proportion diameter/thickness of the tube is weak, and the sharp edge furthest from the pivoting axis suffices then to produce a perfect cut without considerable effort, so that the cut is done xe2x80x9cwhile pullingxe2x80x9d.
In addition, in order to allow the wedging of the tube with a very small diameter so that it does not escape from the seat during the cut, the seat contains on its edge furthest from the pivoting axis a notch where the tube can be seated.
In addition, the effect of the cutting xe2x80x9cwhile pullingxe2x80x9d has the tendency to lead the tube towards the bottom of the seat.